Heat insulating wall structure for a low temperature liquefied gas tank of the membrane type

ABSTRACT

A heat insulating structure for a low temperature liquefied gas tank of the membrane type comprising an outer rigid shell wall, an inner wall of a membrane for containing liquefied gases, and an intermediate layer for supporting the membrane against the outer wall, wherein the intermediate layer is composed of an assembled structure of concrete blocks such as first concrete blocks arranged substantially vertically to the outer wall and second concrete blocks arranged substantially in parallel with said outer wall and supported by said first concrete blocks, at least said first blocks being of heat insulating characteristic, and free spaces within said intermediate layer are filled with heat insulating materials in a powdered and/or granular form.

United States Patent Yamamoto et a1.

[ Sept. 5, 1972 [54] HEAT INSULATING WALL 3,576,270 4/1971 Larsen ..220/10 STRUCTURE FOR A ow 3,118,194 1/1964 Biais ..220/9 LG TEMPERATURE LIQUEFIED GAS 2,999,366 9/1961 La Fave et al. ..62/45 3,566,824 3/1971 Cuneo et al. ..220/9 LG [72] Inventors: Katsuro Yamamoto, Tokyo; Ku- Primary Examiner Meyer p li niyoshi Obata, Kawasaki; Shillji Assistant Examiner-Ronald C. Capossela Nakflgawa, Yokohama, all of Japan AttarneyWaters, Roditi, Schwartz & Nissen [7 3] Assignee: Bridgestone Liquefied Gas Company, Ltd., Tokyo, Japan [57] ABSTRACT A heat insulatin structure for a low tem rature F l d: 21 l 7 g P6 [22] 16 Dec 9 0 liquefied gas tank of the membrane type comprising 1 App]. No.: 100,121 an outer rigid shell wall, an inner wall of a membrane for containing liquefied gases, and an intermediate layer for supporting the membrane against the outer [3O] Forelgn Apphcatlon Pnon'ty Data wall, wherein the intermediate layer is composed of an June 16, 1970 Japan ..45/3877 assembled structure of concrete blocks such as first concrete blocks arranged substantially vertically to the [52] US. Cl. ..220/9 LG, 52/249, 62/45, outer wall and second concrete blocks arranged sub- 220/ l 5 stantially in parallel with said outer wall and supported [51 Int. Cl. ..B65d 25/18 by said first concrete blocks, at least said first blocks [5 8] Field of Search ..220/9 LG, 9 F, 9 M, 10, 15; being of heat insulating characteristic, and free spaces 62/45; 52/249 within said intermediate layer are filled with heat insulating materials in a powdered and/or granular form.

[56] References Cited scl zDm Figures UNITED STATES PATENTS 3,151,416 10/1964 Eakin et al ..62/45 X 0 o 0 a Q 1:: 1: 2 e a 0 Q f l a 0 I S Q 3 6/ 0 a 0 4 t i 0 11 0 U 4 O Q 11 8 u 0 0 Q a l 1/ 0 a J i a a n 0 wa t/j PATENTEDSEP 5 m2 FIG.

FIG.

HEAT INSULATING WALL STRUCTURE FOR A LOW TEMPERATURE LIQUEFIED GAS TANK OF THE MEMBRANE TYPE BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to a heat insulating wall structure, and more particularly to a heat insulating wall structure for use in a tank of the membrane type for containing low temperature liquefied gases such as liquefied petroleum gases which, being normally in the gaseous state at room temperature, are liquefied at a low temperature under atmospheric pressure.

2. Description of the Prior Art The low temperature liquefied gas tank of the membrane type is known and is generally composed of an outer rigid vessel, an inner membranous vessel for containing liquefied gases and a heat insulating intermediate layer disposed between the outer and inner vessels. Since in this wall structure of the tank the internal pressure acting on the inner membranous vessel is transmitted to and supported by the outer rigid vessel through the heat insulating intermediate layer, the heat insulating material constituting the intermediate layer is required to have pressure resisting characteristic as well. Therefore, the intermediate layers of the conventional tanks of the abovementioned membrane type have been made of a heat insulating material having a high compressive strength such as hard foamed polyurethane, balsa or the like. However, these heat insulating materials having a high compressive strength are generally expensive and unfavorably increase the total manufacturing cost of the tank.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a heat insulating wall structure for a low temperature liquefied gas tank of the membrane type wherein an inner wall of a membrane for containing liquefied gases is supported by a rigid outer wall through an intermediate layer of an assembled structure of concrete blocks having heat insulating characteristic, free spaces within said intermediate layer being filled with heat insulating materials in a powdered and/or granular form.

Another object of this invention is to provide the intermediate layer of the assembled structure of concrete blocks, wherein first blocks are arranged substantially vertically to the rigid outer wall and second blocks are arranged substantially in parallel with the rigid outer wall, said second blocks being supported through said first blocks on the rigid outer wall.

Still another object of this invention is to provide the intermediate layer composed of said first and second concrete blocks, wherein said first blocks are made of materials of specially heat insulating characteristic and said second blocks are made of normal materials of not specially heat insulating characteristic.

A further object of this invention is to provide the intermediate layer of the assembled concrete blocks, wherein said concrete blocks are secured to the rigid outer wall by fastening means.

A still further object of this invention is to provide the intermediate layer of the assembled structure of concrete blocks, wherein the inside surface of the assembled structure is lined with a layer of concrete mortar including a wire net therein.

BRIEF DESCRIPTION OF THE DRAWING In the drawing,

FIG. 1 is a horizontally sectional view of an embodiment of the low temperature liquefied gas tank of the membrane type according to this invention; and

FIG. 2 is a part of FIG. 1 showing the details of the wall structure in an enlarged scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a low temperature liquefied gas tank which has the circular horizontal section and is shown in the unloaded condition includes an outer shell wall 1 made of a steel plate properly reinforced by steel structures not shown to have required rigidness. Along the inside surface of the outer wall 1, there are arranged a number of spacers 2 made of concrete blocks having heat insulating characteristic, each one of the blocks of a relatively flat shape being arranged vertically to the outer wall and constantly spaced from adjacent ones. In the manner of bridging the inner ends of each two adjacent blocks, there are provided other concrete blocks 3 of heat insulating characteristic, which form a substantially continuous inner wall arranged substantially in parallel with the outer wall. The concrete blocks of heat insulating characteristic may be made of foam concrete including a number of small bubbles or pearlite concrete. The blocks 2 and 3 may be formed to define openings 2a and 3a, respectively, for the purpose of reducing the weight thereof while keeping sufiicient compressive strength to support the pressure applied from the liquefied gases loaded in the tank.

The inside surface of the wall composed of the blocks 3 may be covered with a lining layer 4 of concrete mortar having heat insulating characteristic. The lining layer is reinforced by a wire net 5 laid within the layer therealong.

The concrete blocks 2 and 3 and the wire net 5 are firmly secured to the outer wall 1 by wire means 6. The wire means maybe so adapted as to be connected with the wire net to fasten the wire net toward the outer wall thereby to fasten the concrete blocks 2 and 3 toward the outer wall, or they may be firmly connected with the concrete blocks as well as the wire net.

The spaces formed between the outer wall and the wall of the concrete blocks 3 are filled with suitable heat insulating materials in a powdered and/or granular form 7 such as pearlite.

A membranous vessel or wall 8 is disposed inside the wall structure formed in the abovementioned manner with rumples at normal temperature for the margin of contraction due to cooling by the low temperature liquefied gases loaded therein.

When the low temperature liquefied gases are loaded in the membranous vessel 8, the rumples of the membrane disappear and the membrane is uniformly supported by the wall formed of the mortar layer and the concrete blocks 3. The pressure applied to the blocks 3 is uniformly distributed to a number of spacers 2 and the heat insulating materials in a powdered and/or granular form filling the spaces between the spacers and is substantially uniformly supported by the outer wall 1.

In the construction of the tank, the spacers 2 and the wall of blocks 3 are formed by laying one concrete block upon another so that the height of the wall of blocks 3 is not less than the height of the membranous vessel 8. However, the spacers may not necessarily be continuous from the bottom to the top thereof as to constitute perfect partitions. The wire means 6 may be replaced by other elongated fastening means such as turn buckles or the like.

From the foregoing, it will be appreciated that this invention provides a superior heat insulating wall structure for a low temperature liquefied gas tank of the membrane type having high structural and compressive strength in a low manufacturing cost by the ingenious combination of the concrete blocks of heat insulating characteristic and the heat insulating materials in a powdered. and/or granular form, wherein the concrete blocks are assembled and fastened to the outer rigid wall in the manner of providing a substantially smooth inside wall for supporting the membranous vessel as well as the spaces to be filled with the insulating materials in a powdered and/or granular form.

It will also be appreciated that the layer 4 of concrete mortar reinforced by the wire net lining the inside surface of the wall of blocks 3 has the effects of strengthening the wall surface which contacts with the membranous vessel and of preventing the crumbling of the wall due to friction applied by the membranous vessel. The layer 4 also has the effect of increasing the structural strength of the intermediate layer composed of the concrete blocks and the heat insulating materials in a powdered and/or granular form by the wire net 5 being fastened to the outer shell wall by the wire means 6.

It is to be noted that the embodiment shown in the drawing and described in the above is not intended to limit the scope of this invention and that various modifications are possible without departing from the scope of this invention. For example, some steel rods may be provided through the openings 2a, 3a to increase the structural strength of the wall structure. In this case, the spaces in the openings provided with the steel rods may be filled with concrete of heat insulating characteristic. Other openings 2a, 3a not provided with the steel rods may be filled with heat insulating materials in a powdered and/or granular form. The concrete blocks 3 forming the wall portion of the intermediate layer may be normal concrete blocks of not specially heat insulating characteristic, if the effect of heat insulation is sufficiently attained by the spacers 2 and heat insulating materials in a powdered and/or granular form 7.

We claim:

1. A heat insulating wall structure for a low temperature liquefied gas tank of the membrane type comprismg a rrgrd outer wall, an rnner wall of a membrane for containing liquefied gases, and an intermediate layer for supporting said inner wall against said outer wall, said intermediate layer being assembled of heat insulating concrete blocks and a heat insulating material of pulverized form, first of said concrete blocks being positioned in spaced relation along the inside surface of said outer wall extending substantially perpendicularly to said outer wall, and second of said concrete blocks being positioned to bridge said first concrete blocks so as to provide a substantially continuous wall of concrete blocks extending substantially in parallel with said outer wall and supported by said first concrete blocks against said outer wall, free spaces being provided between each of said adjacently spaced first concrete blocks as well as between each of said second concrete blocks and said outer wall, said free spaces being filled with said heat insulating material of pulverized form.

2. A heat insulating wall structure according to claim 1, wherein said intermediate layer is secured to the rigid outer wall by fastening means.

3. A heat insulating wall structure according to claim 1, wherein said first concrete blocks are made of specially heat insulating materials.

4. A heat insulating wall structure according to claim 1, wherein the inside surface of said intermediate layer is lined with a layer of concrete mortar including a wire net therein.

5. A heat insulating wall structure according to claim 4, wherein said wire net is secured to the-outer rigid wall by wire means.

6. A heat insulating wall structure according to claim 1, wherein said first and second concrete blocks have openings therein.

7. A heat insulating wall structure according to claim 6, wherein steel rods are provided through said openings to reinforce the assembled structure of said concrete blocks.

8. A heat insulating wall structure according to claim 7, wherein the spaces in said openings around said steel rods are filled with heat insulating materials of pulverized form. 

1. A heat insulating wall structure for a low temperature liquefied gas tank of the membrane type comprising a rigid outer wall, an inner wall of a membrane for containing liquefied gases, and an intermediate layer for supporting said inner wall against said outer wall, said intermediate layer being assembled of heat insulating concrete blocks and a heat insulating material of pulverized form, first of said concrete blocks being positioned in spaced relation along the inside surface of said outer wall extending substantially perpendicularly to said outer wall, and second of said concrete blocks being positioned to bridge said first concrete blocks so as to provide a substantially continuous wall of concrete blocks extending substantially in parallel with said outer wall and supported by said first concrete blocks against said outer wall, free spaces being provided between each of said adjacently spaced first concrete blocks as well as between each of said second concrete blocks and said outer wall, said free spaces being filled wiTh said heat insulating material of pulverized form.
 2. A heat insulating wall structure according to claim 1, wherein said intermediate layer is secured to the rigid outer wall by fastening means.
 3. A heat insulating wall structure according to claim 1, wherein said first concrete blocks are made of specially heat insulating materials.
 4. A heat insulating wall structure according to claim 1, wherein the inside surface of said intermediate layer is lined with a layer of concrete mortar including a wire net therein.
 5. A heat insulating wall structure according to claim 4, wherein said wire net is secured to the outer rigid wall by wire means.
 6. A heat insulating wall structure according to claim 1, wherein said first and second concrete blocks have openings therein.
 7. A heat insulating wall structure according to claim 6, wherein steel rods are provided through said openings to reinforce the assembled structure of said concrete blocks.
 8. A heat insulating wall structure according to claim 7, wherein the spaces in said openings around said steel rods are filled with heat insulating materials of pulverized form. 